Singularity OS is a Microsoft Research Project, a very interesting project: it’s a microkernel OS based on the idea of running everything on managed code (JIT compiled code) including drivers and everything else than the micro-kernel!
The main idea is to get ride of CPU-based memory protection and IO protection, everything is running without any protection, the protection itself is based on static code analysis and dynamic checking. For this to work, any code must in form of an intermediate representation (often incorrectly called bytecode), that is analysed at load, interpreted or compiled on-the-fly with security checks.
The interesting thing is that code is “naturally” protected from buffer overrun, or any kind of attack, as any code is suspect by default, and on the other way switching from one thread to the other is lightning fast as no context change must be done. A very interesting project, that might be bases for future Microsoft or Open-Source OS.
SingularityRelease 2.0 is available here, with it’s source-code.
Microsoft Corporation explain humor to it’s employee, and it’s really funny to read. Maybe the author himself have a great sense of humor, about Corporations and Microsoft! 
Microsoft have 2 table projects that they demonstrated, their Courier prototype, and HP Slate that was a finished product, demonstrated in many occasions…
Courier presented itself as a book, that you may open vertically to read 2 pages at-once (useless, but..), or horizontally with one of the screen becoming a multi-touch keyboard (really great idea!). It was presented on videos and was for Microsoft their future tablet project. They tried to enter this market with different product and this one was the first that doesn’t seems to be based on desktop-os but on a real new seed. Sad it’s cancelled.
HP Slate was totally different, as this is not a prototype of any kind, but a finished product that look like a Chinese copy of an iPad. OS were Windows 7, that was not originally conceived for multi-touch even if it support it, and as any attempt from Microsoft to put it’s desktop OS on a tablet it failed on usability, autonomy, and reactivness. As usual. It’s not a loss, they should have avoided to present it to try to have some buzz before the iPad launch!
When Apple show a new product, a real new product, such as first iMac, iPhone or iPad, please consider the work will be really well done, and you could not tie some generic hardware, a crappy desktop OS or mobile OS, a revised interface, and think you’ll impress anyone or be able to compete!